Separation of molybdenite from copper sulphides



Patented Jan. 23, 1940 ration North American N. Y., a corporation of SEPARATION OF MOLYBDENITE FROM COPPER SULPHIDES Earl H. Brown, Palo Alto, and Carl F. Williams,

San Mateo, Calif., assignors to Minerals Sepa- Corporation, New York, Maryland No Drawing. Application April 17, 1939, Serial No. 268,332

19 Claims.

The present invention relates to a process of flotation concentration for the separation of moiybdenite (molybdenum sulphide) from copper sulphides.

According to the invention, this separationis eifected by treating a pulp of the material containing the molybdenite and copper sulphides in the presence of a substance acting to depress the molybdenite, other agents being also present in .the pulp to effect flotation of the copper sulphides. By the use of the molybdenite depressant, flotation of the molybdenite is only temporarily inhibited. That is, the molybdenite remains in the pulp in such state that its subsequent flotation, if desired, may be readily carried out.

.The basis of the invention, is the discovery that materials of the class consisting of condensation products of aldehydic substances with aromatic sulphonic acids and the salts of these condensation products with salt-forming bases have the property of inhibiting the flotation of molybdenite while not preventing the flotation of copper sulphides.

The aldehydic substance, required for the reaction of condensation by which these molybdenite depressants are obtained, may be formaldehyde. Particularly satisfactory results have been obtained with this substance, although other aldehydes may be used. Both acetaldehyde and butyraldehyde, for example, have been found useful. Instead of the aldehyde itself, of course, a substance capable of yielding the aldehyde under the conditions obtaining in the reaction of condensation may also be used. The term aldehydic substance is thus used herein to include aldehydes and aldehyde-yielding substances.

Thesulphonic acids which may be used for reaction with the ,aldehydic substance are of a large variety. These include the sulphonic acids oi. alkylated and non-alkylated aromatic hydrocarbons. Satisfactory results have thus been obtained with sulphonic acids derived from such hydrocarbons as benzene, para-xylene, naphthalene, alpha methyl naphthalene, and beta methyl naphthalene.

It is probable that the reaction of condensation employed in producing the molybdenite depressants of the invention is one according to which two aromatic sulphonic acid nuclei become connected to the aldehydic carbon atom of the aldehyde as a result of oxygen removal from the aldehyde and hydrogen removal from the sulphonic acid to form water. In the case of the reaction products obtained with formaldehyde,

for example, it is believed that these are of the nature having the two aromatic sulphonic acid nuclei joined through the bivalent methylene radical CH2.

Detailed procedures which have been used in producing the molybdenite depressants of the invention will hereinafter appear in the description of thevexamples of the process.

Although the condensation products themselves are useful in the process, it has usually been found convenient to employ their soluble salts. Their alkali metal and ammonium salts are especially preferred, although their alkaline earth metal salts are also useful.

In carrying out the invention, the molybdenite depressant may be added at any time previous to the flotation of the copper sulphides. Good results have been obtained by adding the molybdenite depressant during the preliminary operation of grinding the ore. In some cases, however, better results have been obtained by add,- ing the molybdenite depressant during the con-. ditioning operation immediately preceding the flotation of the copper sulphides.

The process of this invention may be carried out in either acid, neutral, or alkaline circuits, but it is advisable to determine which type of circuit insures the best results in'each individual case. A few simple preliminary tests, of course,.

are all that is necessary for this purpose.- The pH value of the pulp can be controlled by the usual methods found efiective in the flotation art. The pulp may be made acid by the addition of sulphuric acid or some other acid, while such alkalies as soda ash and lime may be used to render the pulp alkaline.

The flotation of the copper sulphides may be effected by the use of any suitable reagents known in the-art in association with the molybdenite depressant. Collectors that are useful for Certain tests which weremade in reducing the invention to practice will now be described, it being understood that the reagent quantities indicated in these examples are expressed in the usual manner inpounds per ton (2000 lbs.) of dry material treated.

Example 1 To one hundred grams of concentrated sulphuric acid maintained at a temperature of C. were added, over a period of about one hour, one hundred and eleven grams of beta methyl naphthalene. The reaction mixture was maintained for four hours thereafter at the temperature of 160 C. with constant stirring. It was then allowed to cool to 100 C., at which point forty-four grams of water were added. To the diluted mixture maintained at a temperature of 80 C. were then added a total of forty-eight grams of 40% aqueous formaldehyde in successive amounts of twelve grams each at one-hour intervals, the reaction mass being constantly stirred throughout the total period of addition. The temperature was then raised to 100 C. during one hour and thereafter maintained at this temperature for twenty hours. Small quantities of water were added when necessary to keep the mass sufiiciently fluid for eflicient mixing. The material was then further diluted with water, cooled, neutralized with a solution of caustic soda, and filtered, after which the filtrate was evaporated to dryness at a temperature of 100 C. The resulting powder was the sodium salt of the condensation product of formaldehyde with the sulphonic acid of beta methyl naphthalene, which was tested as a molybdenite depressing agent as follows:

Arizona Molybdenum Corporation ore, containing molybdenite and copper sulphides, was ground wet in a ball mill for ten minutes with 1 lb. of the depressing agent per ton of ore, the particle size of the ore being reduced by this operation to minus -mesh. Subsequently, the material in the form of a freely flowing pulp was conditioned in a minerals separation subaeration flotation machine with 0.3 lb. of potassium ethyl xanthate and 0.15 lb. of steam distilled pine oil, both per ton of feed, after which a rough concentrate of copper was removed in the usual manner by flotation. The remaining pulp was then conditioned with 0.1 lb. of steam distilled pine oil and 0.4 lb. of kerosene, both per ton of feed, its subsequent frothing in the machine yielding a rough concentrate of molybdenum.

The results of the test are given in the following table:

Assays Distribution Percent weight Percent Percent Percent Percent Cu MOS: Cu M08:

Example 2 A molybdenite depressing agent was prepared in the same manner as described in Example 1 with the only difl'erence that alpha methyl naph-' -thalene was used am starting material for redenite depressing agent inclusive of the reaction of condensation were otherwise substantially the same as in Example 1. The molybdenite depressing agent finally obtained in the form of a dry powder was thus the sodium salt of the condensation product of formaldehyde with naphthalene, beta sulphonic acid. Arizona Molybdenum Corporation ore was ground with this agent used at the rate of 1.1b. per ton of ore. A copper float was first produced by the use of 0.3 lb. of potassium ethyl xanthate and 0.15 lb. of steam distilled pine oil, both per ton of feed, after which a molybdenum float was separated from the residue by the use oi 0.15 lb. of steam distilled pine oil and 0.4 lb. of kerosene, both per ton of feed. The results were as follows:

When the amount of the depressing agent of Example 3 was reduced to 0.5 lb. per ton of ore,

. the following results were obtained:

Assays Distribution Percent weight Percent Percent Percent Percent Cu MoSs Cu 0 4. 03 30. 16 5. 08 87. 97 18. 37 2. 58 3.18 35. 25 5. 94 81. 63 93. 39 0.09 Trace 6. 09

Example 5 Using previously prepared benzene sulphonic acid purchased on the market as a starting material, the sodium salt of the condensation product of formaldehyde with this sulphonic acid was obtained in substantially the same manner as before, the following test being carried out on this agent:

Arizona Molybdenum Corporation ore was ground to minus 65-mesh in the absence of the molybdenite depressing agent. A freely flowing pulp of the ground ore was first thoroughly mixed with 4 lbs. of the depressing agent and 36.8 lbs. of sulphuric acid, both per ton of ore, after which it was mixed with 0.1 lb. of potassium ethyl xanthate and 0.15 lb. of steam distilled pine oil, both per ton of ore. Subsequent frothing of the pulp yielded a rough concentrate of copper. The rein this instance were as follows: malning P p Was then mixed with 0f steam distilled pine oil and 0.2 lb. of kerosene, Assays Distribution both per ton of ore, its subsequent i'rothing yieldf fi ing a' rough concentrate oi molybdenum. we a Pment Percent Yemen The results of the test were the following:

On MoBs Cu M08:

Assays Distribution 100.0 1.42 1.10 100.0 100.0

4.50 ease 4.02 00.02 15.22 f 3.49 s20 28.87 5.42 84.78 t Percent Percent Percent Percent 92.01 0.01 rises 4.50 Cu 05, Cu Mos,

3 is 2'? as. "it Here already prepared naphthalene beta sul- 2:90 00 3010 13100 82:32 phonic acid obtained from the Eastman Kodak M5 Company was used for reaction with formaldehyde. The procedures of preparing the molyb- The pH value of the tailing was 5.9.

Example 6 In a parallel test carried out under the same conditions as in Example 5, the sodium salt of the I condensation product of formaldehyde with the sulphonic acid of paraxylene yielded the results indicated in the following table:

Assays Distribution Percent weight Percent Percent Percent Percent Ou M05: 011 MOS:

4. 16 10. 88 l. 70 76. 83 5. 30 3. 97 2. 28 31. 15. 37 94. 70 91. 87 0. 05 None 7. 80

Example 7 Formaldehyde was condensed with naphthalene sulphonic acid, the resulting product being used as such in the following test:

per ton of ore. The material was then transferred to a flotation machine where it was treated with 0.3 lb. of potassium ethyl xanthate and 0.15 lb. of steam distilled pine 011, both per ton of ore, to give a copper concentrate. Thereafter, the residue was treated with 0.1 lb. of steam dis- T tilled pine oil and 0.4 lb. of kerosene, both per ton of ore, to give a molybdenum concentrate.

The results of the test were as follows:

Assays Distribution Percent weight Percent Percent Percent Percent C M082 Cu M082 100. o 0. 57 '1. as 100. 0 100. 0

4. 28 10. 32 9. 15 76. 94 28. 48 2. 23 2. 58 10 10. 03 71. 52 93. 49 0. 08 Trace 13. 03

Example 8 The condensation product of Example -7 was neutralized with caustic soda and subsequently filtered, after which the filtrate was evaporated to dryness. The dry powder thus obtained was used in a test identical in every respect to the test of Example 7. The results in this instance when ammonium hydroxide was used to neu-,

tralize the condensation product of Example '1,

the following results were obtained:

, Assays Distribution Percent weight Percent Percent Percent Percent Cu Mos, Cu Mo 4. 1o 9. 52 7. 70 75. 02 21. 21 1.83 4.12 65.00 14.29 78 79 94. 01 0. 06 None 10. 60

Example 10 The depressing agent of Examples 3 and 4 (the sodium salt of the condensation product of formaldehyde with naphthalene beta sulphonic acid) was here used in the following manner:

A pulp of Arizona Molybdenum Corporation ore was treated with 0.2 lb. of potassium ethyl xanthate and 0.2 lb. of steam distilled pine oil. both per ton of ore, to give a rougher bulk flotation concentrate of copper and-molybdenum, a final tailing being obtained. The rougher bulk concentrate was conditioned for five minutes with 0.25 lb. of the depressing agent per ton of ore, after which it was treated with 0.05 lb. of steam distilled pine oil, 0.05 lb. of potassium ethyl xanthate, and 0.05 lb. of potassium amyl xanthate, all per ton of ore, to give a flotation concentrate of copper. The unfloated residue from this operation constituted the molybdenum concentrate.

The results of the test were as follows:

Assays Distribution Percent weight Percent Percent Percent Percent Cu M08: Cu M08:

v100. 0 0. 56 l. 35 .3. 63 12. 00 0. 78 2. 73 1. 80 48. 30 93. 64 0. 08 Trace Example 11 The depressing agent of Example 1 (the sodium where, in the form of a freely flowing pulp made acid with 36.8 lbs. of sulphuric acid-per ton of ore, it was conditioned for two minutes with 1 lb. of the inhibiting agent per ton of ore. A rough concentrateof copper was first produced by the use of 0.2 lb. of potassium ethyl xanthate and 0.15 lb. of cresylic acid, both per tonof ore, after which a molybdenum concentrate was separated from the residue by the use of 2 lbs. of sodium carbonate, 0.7 lb. of kerosene, and 0.2 lb. of steam distilled pine oil, all per ton of ore.

The following results were obtained:

Assays Distribution Percent weight Percent Percent Example .12

- Acetaldehyde was condensed with naphthalene sulphonic acid, the resulting product being used in its natural acid state as follows:

Arizona Molybdenum Corporation ore was ground in a ball mill for ten minutes with 4 lbs. of the inolybdenite depressing agent per ton of ore. In the form of a freely flowing pull it was then treated in a flotation machine with 0.3 lb. of potassium ethyl xanthate and 0.15 lb. of steam distilled pine oil, both per ton of ore, to give a concentrate of copper. Thereafter, the residue was treated with 0.15 lb. of steam distilled pine oil and 0.4 lb. of kerosene, both per ton of ore, to give a concentrate of molybdenum.

The results of the test were as follows:

I Assays Distribution Percent weight Percent Percent Percent Percent Cu MoS-z Cu M05:

4. 76 9. 56 9. 60 82. 53 34. 68 2. l3 1. 9O 40. 10 7. 35 65. 32 93. 11 0. 06 None 10. 12

Example 13 Butyraldehyde was condensed with naphthalene sulphonic acid, the resulting product being used in its natural acid state as follows:

Arizona' Molybdenum Corporation ore was ground in a ball mill for ten minutes with 30 lbs. of the molybdenite depressing agent per ton of ore. In the form of a freely flowing pulp it was then treated in a flotation machine with .3 lb. of potassium ethyl xanthate and 0.15 lb. of steam distilled pine oil, both per ton of ore, to give a concentrate of copper. Thereafter, the residue was treated with 0.3 lb. of steam distilled pine oil, 0.75 lb. of kerosene, and 0.1 lb. of oresylic acid, all per ton of ore, to give a concentrate of molybdenum.

The results of the test were as follows:

Assays D istribu tion Percent weight Percent Percent Percent Percent Cu M081 Cu M081 Head 100.0 0. 608 1.43 100.0 100. 0 Cu 0011c 7. 56 6. 24 2. 2 77. 63 ll. 62 Mo cone ll. 07 0. 86 9. 0 15. 67 69. 61 81. 37 0. 05 0. 33 0. 70 18.77

The effectiveness of the molybdenite depressants of the invention is clearly shown by the foregoing examples, it being understood that the copper and molybdenum concentrates obtained in these examples were rougher concentrates which, in practice, would be raised to commercial grade in accordance with the customary procedures of retreatment.

In the following claims, the term copper sulphide" should be construed as covering one or more copper sulphides.

What is claimed is 1. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of aldehydic substances with aromatic sulphonic acids and the salts of these condensation products with saltforming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

2. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide de-v pressing agent selected from the class consisting of the condensation products of aldehydic substances with aromatic sulphonic acids and the ammonium, alkali-metal and alkaline-earthmetal salts of these, condensation products so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

3. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of aldehydic substances with aromatic sulphonic acids and the am.- monium, alkali-metal and alkaline-earth-metal salts of these condensation products so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide, and subsequently subjecting the residue to a flotation operation yielding a molybdenum sulphide concentrate.

4. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a .flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of aldehydic substances with sulphonic acids of aromatic hydrocarbons and the salts of these condensation products with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

5. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of formaldehyde with aromatic sulphonic acids and the salts of these condensation products with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

6. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of formaldehyde with aromatic sulphonic acids and the ammonium, alkali-metal and alkaline-earth-metal salts of these condensation products so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide, and subsequently subjecting the residue to a flotation operation yielding a molybdenum sulphide concentrate.

7. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of formaldehyde with sulphonic acids of aromatic hydrocarbons and the salts of these condensation products with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

8. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of formaldehyde with sulphonic acids of allnylated aromatic hydrocarbons and the salts of these condensation products with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

9. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphidesto a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of formaldehyde with sulphonic acids of polynuclear aromatic hydrocarbons and the salts of these condensation products with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

10. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material contain ing said sulphides to a flotation operation inthe presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of formaldehyde with sulphonic acids of alkylated polynuclear aromatic hydrocarbons and the salts of these condensation products with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

11. A process of flotation concentration for the separation of copper and molybdenum sulphides,

which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of formaldehyde with sulphonic acids of benzene and the salts of these condensation products with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

12. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of formaldehyde with sulphonic acids of aromatic hydrocarbons of the benzene series and the salts of these condensation products with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

13. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of formaldehyde with sulphonic acids of naphthalene and the salts of these condensation products with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

14. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of formaldehyde with sul- -atio n yielding 5 phonic acids of aromatic hydrocarbons of thenaphthalene series and the salts of these condensation products with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

15. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the alkali metal and ammonium salts of the condensation products of formaldehyde with sulphonic acids of aromatic hydrocarbons so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

16. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of compounds having at least one methylene group connected to two aromatic sulphonic acid nuclei and the salts of these compounds with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

17. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of compounds having at least one methylene group connected to two naphthalene sulphonic acid nuclei and the salts of these compounds with salt-forming bases so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

'18. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a flotation operation in the presence of a molybdenum sulphide depressingagent selected from the class consisting of the condensation products of acetaldehyde with sulphonic acids of aromatic hydrocarbon and the ammonium, alkali-metal and alkalineearth-metal salts ofthese condensation products so as to produce a concentrate of copper sulphide with a rejection of molybdenum sulphide.

19. A process of flotation concentration for the separation of copper and molybdenum sulphides, which comprises subjecting the material containing said sulphides to a preliminary flotation opera bulk concentrate of said sulphides, and subjecting said bulk concentrate to a flotation operation in the presence of a molybdenum sulphide depressing agent selected from the class consisting of the condensation products of aldehydic substances with aromatic sulphonlc acids and the ammonium, alkali-metal and alkaline-earth-metal salts of these condensation products so as to produce a concentrate of copper sulphide with a. rejection of molybdenum sulphide.

EARL H. BROWN. CARL F. WILLIAMS. 

